It is known to provide a motor vehicle with a sliding door to permit entry to and exit from a motor vehicle. In the case of a manually operated sliding door the opening and closing forces applied to the door due to gravity when the vehicle rests upon a slope can be considerable. Such gravity forces can produce excessive relative velocity between the sliding door and the structure of the motor vehicle when the slope is steep that can cause damage to components associated with the sliding door such as tracks, rollers, bump-stops when an end limit of door movement is reached.
Such damage can be costly and time consuming to repair and often requires expensive bump stops to be provided to reduce the risk of damage from occurring.
FIGS. 1a to 1c show a motor vehicle 110 having a left hand side rear opening door 112 in three positions and the direction in which a force resulting from the angle of the slope upon which the motor vehicle rests act upon the sliding door.
In FIG. 1a the motor vehicle 110 is resting upon a surface a′ that is horizontally disposed such that a longitudinal axis H-H of the motor vehicle 110 is disposed horizontally and an upright axis v-v of the motor vehicle 110 is disposed vertically. The sliding door 112 is shown in a closed position and is moveable between respective closed and open positions as indicated by the double arrow C-O. Movement of the sliding door 112 in a closing direction is indicated on FIG. 1a by “C” and movement of the sliding door 112 in an opening direction is indicated on FIG. 1a by “O” and movement between the two positions “O” and “C” is guided by tracks that are disposed horizontally when the motor vehicle 110 is resting on a horizontal surface. It will be appreciated that when the motor vehicle 110 is resting on a horizontal surface no force due to the effect of gravity will affect either closing or opening of the sliding door 112 because such a gravity force will act vertically in a downward direction pushing the sliding door onto the tracks.
In FIG. 1b the motor vehicle 110 is shown resting on a slope referred to herein as a ‘decline’. That is to say, on a slope where a front end of the motor vehicle 110 is lower than a rear end of the motor vehicle 110. The magnitude of the decline is indicated by the angle θ of the surface ‘R’ on FIG. 1b. A force due to gravity or ‘gravity force’ acts upon the sliding door 112 in the direction of the arrow F due to the inclined orientation of the motor vehicle and the tracks used to support the sliding door 112. The effect of this gravity force is to urge the sliding door 112 in the door closing direction thereby producing undesirable acceleration and relative velocity of the sliding door 112 if the decline is a steep one. The magnitude of the force “F” is equal to mg sin θ. Where m is equal to the mass in kg of the sliding door 112, g is equal to 9.81 m/s2 and θ is the angular orientation of the surface ‘R’ to horizontal.
In FIG. 1c the motor vehicle 110 is shown resting on a slope referred to herein as an ‘incline’. That is to say on a slope where a front end of the motor vehicle 110 is higher than a rear end of the motor vehicle 110. The magnitude of the incline is indicated by the angle Φ on FIG. 1c. The gravity force acting upon the sliding door 112 is in the direction of the arrow f. The effect of this gravity force is to urge the sliding door 112 in a door opening direction thereby producing undesirable acceleration and relative velocity of the sliding door 112 if the incline is a steep one. The magnitude of the force “f” is equal to mg sin Φ. Where m is equal to the mass in kg of the sliding door 112, ‘g’ is equal to 9.81 m/s2 and Φ is the angular orientation of the surface ‘R’ to horizontal.
Therefore, in summary, whenever a vehicle is resting on a slope in which the orientation of the motor vehicle is non-horizontal a gravity force will act upon a sliding door biasing the sliding door either open or closed depending upon the orientation of the slope. The application of this gravity force upon the sliding door can result in unwanted and potentially damaging sliding door speed if the orientation of the slope produces a gravity force in the same direction as the direction in which the door is being moved.
It is an object of this disclosure to provide a vehicle with a sliding door having a simple and economical to manufacture brake mechanism to reduce the relative velocity between the sliding door and the body structure of the vehicle when the sliding door is moved while the vehicle is resting on a slope.
According to the disclosure there is provided a vehicle having an elongate track extending longitudinally along a side of the motor vehicle, a sliding door manually slideable between closed and open positions and a sliding door brake mechanism for selectively applying a braking force to the sliding door. The sliding door brake mechanism comprises a brake member pivotally connected to the sliding door of the vehicle for rotation about a pivot axis and having a brake surface located between the pivot axis of the brake member and the adjacent elongate track. The brake member is rotatable about the pivot axis between a neutral position in which there is no contact between the brake surface and the adjacent elongate track and an engaged position in which the brake surface abuts against the adjacent elongate track so as to provide a braking force to the sliding door. When the vehicle is on a slope, the non-horizontal orientation of the vehicle due to the slope upon which it rests causes the brake member to be automatically engaged thereby providing the braking force to the sliding door.
The brake member may comprise a pair of spaced apart brake surfaces located on opposite sides of a plane aligned with and extending from the pivot axis to the elongate track.
There may be a first brake surface positioned between the plane and a rear end of the sliding door and the first brake surface may be automatically brought into engagement with the elongate track when the vehicle is on an incline.
The braking force produced by the engagement of the first brake surface with the elongate track may produce a self-servo effect when the sliding door is moved in a door opening direction while the vehicle is on the incline.
There may be a second brake surface positioned between the plane and a front end of the sliding door and the second brake surface may be automatically brought into engagement with the elongate track when the vehicle is on a decline.
The braking force produced by the engagement of the second brake surface with the elongate track may produce a self-servo effect when the sliding door is moved in a door closing direction while the vehicle is on the decline.
The brake member may include an actuator having a moveable component the position of which is dependent upon the orientation of the vehicle. The moveable member may be spaced away from the pivot axis of the brake member on an opposite side of the pivot axis to the position of the or each brake surface so that movement of the moveable component provides a force to the brake member to cause the brake member to rotate about the pivot axis in a direction corresponding to the orientation of the vehicle.
The actuator may have a body defining a cavity and the moveable component may be one of a ball and a roller held captive in the cavity in the body of the actuator.
The body of the actuator may be formed as a unitary part of the brake member.
Preferably, the elongate track may be a sliding door support track extending longitudinally along a side of the motor vehicle and the sliding door may be manually moveable along the sliding door support track between the closed and open positions.
The brake member may be pivotally connected to the sliding door via a carrier forming part of a sliding door support mechanism.
The sliding door support mechanism may further comprise one or more wheels rotatably connected to the carrier for engaging the sliding door support track and the brake member may be positioned such that a portion of the sliding door support track is interposed between the brake member and one or more of the wheels.
Each brake surface may be formed on a brake portion of the brake member and each brake portion may be formed as a unitary part of the brake member.
The pivot axis of the brake member may be arranged substantially vertically when the vehicle rests upon a level horizontal surface.
The direction in which the brake member rotates when the vehicle is on the slope is related to the direction in which the pivot axis is displaced from the vertical due to the vehicle resting on the slope.